For converting analogue telephone signals from a particular subscriber across a particular line, repeaters are used to provide two different signal paths. In one of these paths the analogue signals are coded to the PCM-coded signals and in the other a decoding of the digital PCM-coded signal flow is carried out. Furthermore, amplifiers are used to compensate for the attenuation of the line. It is also known to use a direct current magnetized hydrid transformer for dividing the input of a repeater towards the two-wire line, the transformer feeding the desired current to the subscriber's set connected to the line. At the same time, a DC-magnetizing of the transformer core is obtained.